1. Field of the Invention
The present invention relates to a connection unit and a vehicle incorporating the connection unit. More particularly, the present invention relates to a connection unit employed in a vehicle having a plurality of power storage devices switched for usage.
2. Description of the Background Art
In recent years, electric cars, hybrid vehicles, fuel-cell vehicles and the like have been developed and adapted to practical use as environment-friendly vehicles. These vehicles are incorporated with a motor and a power storage device for driving the motor.
Japanese Patent Laying-Open No. 2008-167620 discloses a power supply device for a vehicle having a plurality of externally chargeable batteries switched for usage.
It is desirable that the distance an electric vehicle can run by one charging operation is as long as possible. Likewise with a hybrid vehicle that incorporates an internal combustion engine, a storage battery, and a motor, it is desirable that the running distance allowed per one charge without using the internal combustion engine is as long as possible in the case of employing a configuration in which the storage battery can be charged from an external source.
In order to increase the running distance allowed by one charge, the amount of energy of the battery incorporated in a vehicle must be increased. One approach is to incorporate a plurality of power storage devices into the vehicle. Although the required capacitance can be ensured by connecting battery cells in parallel, there may be the case where the capability of all the batteries incorporated will not be thoroughly depleted due to only some of the batteries first becoming degraded. In this context, another approach is to provide a plurality of batteries in a switchable manner, allowing the batteries to be depleted equally by switching to another battery when one is depleted.
However, if a connection unit similar to that of a conventional case (a junction box) is provided per one battery in vehicles operating with switching power supplies, more relays will be required, leading to the problem of increase in weight and cost.